This application claims benefit of Japanese Patent Application No. 2000-289869 filed on Sep. 25, 2000, the contents of which are incorporated by the reference.
The present invention relates to temperature controllers and light-waveguide devices using these temperature controllers. More specifically, the present invention concerns temperature controllers for temperature controlling light-waveguides or like parts as subject of temperature control requiring highly accurate temperature control as accurately as possible and light-waveguide devices with such temperature controller.
Light-waveguides provide outputs of varying wavelengths depending on the ambient temperature of their installation spots.
FIG. 7 shows a light-waveguide device 11 as an example of the light-waveguide. An input side fiber array 13 is mounted on one end of the device 11 for connecting input fibers 12 thereto. An output side fiber array 15 is mounted on the other end of the device 11 for connecting output fibers 14 thereto. The device 11 has an array 16 of a plurality of channel waveguides disposed in a fashion of being curved in a predetermined direction with different radii of curvature in its substantially central position. An input side and an output side slub waveguides 17 and 18 are connected to the incidence and emission sides, respectively, of the channel waveguide array 16. Input and output waveguides 19 and 20 are disposed between the input side fiber array 13 and the input side slub waveguide 17 and between the output side slab waveguide 18 and the output side fiber array 15, respectively.
In this light-waveguide device 11, multiplexed signal light beams incident from the input waveguides 19 on the input side slab waveguide 17 are let to proceed along expandingly spaced-apart paths to be incident in in-phase relation to one another on the channel waveguide array 16. In the channel waveguide array 16, predetermined optical path length differences are provided along the constituent waveguides such that the optical path lengths thereof are progressively longer or shorter. Thus, light beams that are propagated through the constituent waveguides reach the output side slab waveguide 18 in phases different from one another at a predetermined interval. Actually, waveguide dispersion is present, and thus the in-phase place is tilted depending on the wavelength. As a result, the light beams are focused (or converged) in the interface between the output side slab waveguide 18 and the output waveguides 20 at different positions of the plane in dependence on the wavelengths. A given wavelength component thus can be taken out from each of the output waveguides 20, which are disposed at positions corresponding to the wavelengths.
In this light-waveguide device 11, variations of the temperature of the zone, in which the input side slab waveguide 17, the channel waveguide array 16 and the output side slab waveguide 18 are disposed, result in variations of the refractive index of the quartz glass itself constituting the zone, thus varying the slab length and the optical lengths of the channel waveguides. For example, with a temperature rise, the wavelength is shifted toward the longer wavelength side, thus increasing the optical loss.
Therefore, it has been in broad practice to control the temperature to be constant by cooling the light-waveguide device with a Peltier element. In this method, the device may be connected to a temperature sensor by disposing the device on the Peltier element. In this case, a problem is posed that the temperature of the device can not be controlled uniformly if the Peltier element is smaller in size than the device.
FIG. 8 shows an example of the temperature controller, which is proposed in Japanese Laid-Open No. 9-179078 as a solution to this problem. The illustrated temperature controller has a heat conductor member 33, which is mounted such as to commonly cover to portions of a pair of temperature control elements 31 and 32. A light-waveguide device 35 is mounted on the heat conductor member 33 via an intervening heat conductor medium 34 such as heat conductor grease. A temperature sensor 36 is disposed in a central portion of the heat conductor member 33 intermediate between the pair temperature control elements 31 and 32, and detects the temperature of this portion. The temperature sensor 36 outputs its temperature detection output to a temperature controller means 37, which controls the driving of the pair temperature control elements 31 and 32 to control the detected temperature to be constant.
In this proposed temperature controller, the heat conductor medium 34 is constant temperature controlled via the heat conductor member 33 having a certain heat capacity and thus without being influenced by the ambient temperature. For the temperature detection, the temperature sensor 36 is buried in the heat conductor member 33.
This prior art temperature controller uses two relatively small temperature control elements 31 and 32 for the temperature control of the light-waveguide 35. For uniform temperature control of the light-waveguide 35, the single heat conductor member 33 is interposed over the temperature control elements 31 and 32. For uniform temperature control of the light-waveguide 35, however, the heat conductor member 33 should have a certain great heat capacity. Therefore, a problem is posed that the temperature controller itself consumes increased power.
In the meantime, the temperature sensor 36 is buried in the heat conductor member 33 in an ordinary way such as providing a slight recess. In this case, the temperature-detecting tip of the temperature sensor 36 is enclosed in the heat conductor member 33. Thus, compared to the case of mounting the temperature sensor 36 on the outer surface of the heat conductor member 33, the temperature sensor 36 is less subject to the influence of the external temperature.
This temperature controller, however, has a problem that it is impossible to temperature control the light-waveguide 35 with sufficiently high accuracy even by enclosing the portion of the light-waveguide 35 with a heat-insulating member (not shown) or by enclosing the portion including the temperature control elements 31 and 32 as well as the light-waveguide 35 likewise with a heat-insulating member (not shown). The inventor of this invention confirmed that the most significant cause of this problem is that the temperature sensor 36 itself, such as thermistor, picks up the external temperature condition.
FIG. 9 expresses an example of the temperature sensor. While this example concerns a thermistor, the temperature sensor 36 has a temperature sensing portion 41 constituting its tip and a pair of leads 42 and 43 and a pair of lead lines 42 and 43. The distal ends of the pair lead lines 42 and 43 are connected to electric wires or the like (not shown) on the side of the temperature control means 37 for the transmission of a signal representing the temperature.
In the temperature sensor 36, the temperature sensing portion 41 at the tip is partly or fully buried in the heat conductor member 33. In some case, end portions of the lead lines 42 and 43 are buried. Most portion of the lead lines 42, 43 are, however, exposed to the outside of the hest conductor member 33. These lead lines 42 and 43 thus pick up the ambient temperature condition, and change the detected temperature itself of the temperature sensing portion 41.
To avoid this influence, it is conceivable to adopt such measure as cutting off portions of the lead lines 42 and 43 exposed to the outside of the heat conductor member 33 and connecting these portions to thicker electric wires or soldering these portions to a printed circuit board. In such case, however, the temperature of the electric wires or the soldered portions has greater influence on the temperature sensing portion 41. Therefore, such arrangement can not solve the problem.
An object of the present invention accordingly is to provide a temperature controller, which can reduce the influence of the ambient temperature of the lead line portions as much as possible to permit temperature control of the temperature control subject parts or components, particularly light-waveguide device, with high accuracy, and a light-waveguide device with such temperature controller.
According to the invention (1), there is provided a temperature controller comprising: a temperature control element serving for heating or cooling; a temperature control subject component which is temperature controlled by the temperature control element; a heat conductor member intervening between the temperature control subject component and the temperature control element and having a space in the form of a curve drawn with a single stroke from a predetermined position on the inner side of an edge up to a predetermined side edge portion, the curved space having a predetermined length; a temperature sensor including a temperature sensing tip disposed in the curved space of the heat conductor member at the predetermined position thereof and relatively thin lead lines led out from the temperature sensing tip, the lead lines being led together with a filler buried therewith through the curved space in the heat conductor member and having end potions led out from the side edge portion to the outside; and a temperature control means for driving the temperature control element on the basis of the result of temperature detection by the temperature sensor.
Specifically, according to the invention (1), the heat conductor member which is disposed such as to intervene between the temperature control element such as a Peltier element and the temperature control subject component such as a light-waveguide element, is formed with the space in the form of a curve with a single stroke from a predetermined position on the inner side of an edge of it (which may not be the central position) up to a predetermined side edge portion, and the temperature sensing tip of the temperature sensor is disposed in a space portion corresponding to the predetermined position noted above, and the relatively thin lead lines are led together with a filler buried therewith through the curved space in the heat conductor member and have their end portions led out to be exposed to the outside. Thus, it is possible to substantially ignore heat return from the exposed lead portions to the temperature sensing tip of the temperature sensor, that is, it is possible to obtain highly accurate temperature control by the temperature control means.
According to the invention (2), there is provided the temperature sensor according to the invention (1), wherein the heat conductor member is in the form or a rectangular plate having one surface thereof formed with a space in the overall form of a rectangular spiral curve with progressively increasing sides from the position, at which the temperature sensing tip of the temperature sensor is buried.
Specifically, according to the invention (2), the curved space with the temperature sensor element disposed therein is in a rectangular spiral form such as to correspond to the shape of the heat conductor member.
According to the invention (3), there is provided the temperature controller according to the invention (1), wherein the temperature control element is a Peltier element having a cooling surface, while the temperature control subject component is a light-waveguide element.
Specifically, according to the invention (3), the light-waveguide element is cooled by the Peltier element as a specific example of high accuracy temperature control. The temperature control element need not be one for cooling, and it may be an element or component (hereinafter referred to as element in general) for temperature increasing control. Such a heater type temperature control element may be such element as a silicon rubber heater made of silicon rubber, a ceramic heater, a nicrome heater, etc. as well.
According to the invention (4), there is provided the temperature controller according to the invention (3), wherein the heat conductor member is a metal plate greater in size than the Peltier element in contact with it.
Specifically, according to the invention (4), the heat conductor member is formed from an excellently heat conductive metal plate greater in size than the Peltier element, and thus it permits temperature control of the temperature control subject component in a wide range. As the metal plate, a copper plate is excellent in the heat conductivity and also in view of the cost. However, the metal member may also be one of other metal such as aluminum.
According to the invention (5), there is provided the temperature controller according to the invention (1), wherein the curved space is a groove formed in the metal surface on the side of the temperature control subject component.
Specifically, according to the invention (5), a groove is formed as the space. It is also possible to form the space by stamping off the metal itself.
According to the invention (6), there is provided the temperature controller according to the invention (1), wherein the lead lines of the temperature sensor are relatively thin electric wires for reducing the heat return ratio.
Specifically, according to the invention (6), relatively thin electric wires are used as the lead lines to reduce the ratio of heat return to the temperature sensing tip of the temperature sensor.
According to the invention (7), there is provided the temperature controller according to the invention (1), wherein the curved space formed in the heat conductor member in the form of a line drawn with a single stroke from the predetermined position up to the predetermined side edge portion extends in a folded fashion along a curved line approaching in from the predetermined position to the predetermined side edge portion.
Specifically, according to the invention (7), the single stroke curved space may not be spiral in form, and it may also be of a folded line form. Where such a curved line space is locally present in a position of the heat conductor member, the predetermined position noted above naturally may not be at the central position of the heat conductor member.
According to the invention (8), there is provided a temperature controller comprising a temperature control element serving for heating or cooling, a temperature control subject component which is temperature controlled by the temperature control element and a plate intervening between the temperature control subject component and the temperature control element, and a temperature sensing element including a temperature sensing tip for detecting temperature and lead lines led out from the temperature sensing tip, wherein: the temperature sensing tip is disposed in the plate; and the lead lines have portions disposed in a bent fashion from the position of the temperature sensing tip up to an edge of the plate.
Thus, by the portions disposed in a bent fashion the heat return to the temperature sensing tip of the temperature sensor via the bent line portions can be substantially ignored, and it is thus possible to obtain high accuracy temperature control.
According to the invention (9), there is provided a temperature controller comprising a temperature control element serving for heating or cooling, a temperature control subject component which is temperature controlled by the temperature control element and a plate intervening between the temperature control subject component and the temperature control element, and a temperature sensing element including a temperature sensing tip for detecting temperature and lead lines led out from the temperature sensing tip, wherein: the temperature sensing tip is disposed in the plate; and the lead lines have spirally disposed portions from the position of the temperature sensing tip up to an edge of the plate.
Thus, by the spirally disposed portions the heat return to the temperature sensing tip of the temperature sensor via the bent line portions can be substantially ignored, and it is thus possible to obtain high accuracy temperature control.
According to the invention (10), there is provided a temperature controller comprising a temperature control element serving for heating or cooling, a temperature control subject component which is temperature controlled by the temperature control element and a plate intervening between the temperature control subject component and the temperature control element, and a temperature sensing element including a temperature sensing tip for detecting temperature and lead lines led out from the temperature sensing tip, wherein: the temperature sensing tip is disposed in the plate; and the lead lines have meanderingly disposed portions from the position of the temperature sensing tip up to an edge of the plate.
Thus, by the meanderingly disposed portions the heat return to the temperature sensing tip of the temperature sensor via the bent line portions can be substantially ignored, and it is thus possible to obtain high accuracy temperature control.
According to the invention (11), there is provided the temperature controller according to one of the invention (8) to (10), wherein: the plate has a space, in which the temperature sensing tip and the lead lines are disposed; and the space in which the temperature sensing tip and the lead lines are disposed are filled with a resin.
Specifically, according to the invention (11), the curved space in which the temperature sensing tip and the lead lines are disposed, are filled with a resin, and heat transmitted from the outside via the lead liens escapes through the resin to the plate side. Thus, the heat return to the temperature sensing tip can be substantially ignored.
According to the invention (12), there is provided the temperature controller according to the invention (11), wherein the plate is a metal plate.
Specifically, according to the invention (12), a highly heat conductive metal plate is used. This is, however, by no means limitative. For example, a silicon plate may be used. It is further possible to use various other excellently heat conductive sheets or films.
According to the invention (13), there is provided a light-waveguide device with a temperature controller comprising a temperature control element serving for heating or cooling, a temperature control subject component which is temperature controlled by the temperature control element, a heat conductor member intervening between the temperature control subject component and the temperature control element and having a space in the form of a curve drawn with a single stroke from a predetermined position on the inner side of an edge up to a predetermined side edge portion, the curved space having a predetermined length, a temperature sensor including a temperature sensing tip disposed in the curved space of the heat conductor member at the predetermined position thereof and relatively thin lead lines led out from the temperature sensing tip, the lead lines being led together with a filler buried therewith through the curved space in the heat conductor member and having end potions led out from the side edge portion to the outside, and a temperature control means for driving the temperature control element on the basis of the result of temperature detection by the temperature sensor; and a light-waveguide element temperature controlled by the temperature controller.
Specifically, according to the invention (13), the light-waveguide device with temperature controller is obtained by combining the temperature controller as defined in the invention (1) according to the invention and the light-waveguide element, thus permitting highly accurate temperature control of the light-waveguide device.
According to the invention (14), there is provided a light-waveguide device with a temperature controller comprising a temperature control element serving for heating or cooling, a temperature control subject component which is temperature controlled by the temperature control element and a plate intervening between the temperature control subject component and the temperature control element, and a temperature sensing element including a temperature sensing tip for detecting temperature and lead lines led out from the temperature sensing tip, wherein the temperature sensing tip is disposed in the plate; and the lead lines have portions disposed in a bent fashion from the position of the temperature sensing tip up to an edge of the plate; and a light-waveguide element temperature controlled by the temperature controller.
Specifically, according to the invention (14), the light-waveguide device with temperature controller is obtained by combining the temperature controller as defined in the invention (8) according to the invention and the light-waveguide element, thus permitting highly accurate temperature control of the light-waveguide device.
According to the invention (15), there is provided a light-waveguide device with a temperature controller comprising a temperature control element serving for heating or cooling, a temperature control subject component which is temperature controlled by the temperature control element and a plate intervening between the temperature control subject component and the temperature control element, and a temperature sensing element including a temperature sensing tip for detecting temperature and lead lines led out from the temperature sensing tip, wherein the temperature sensing tip is disposed in the plate and the lead lines have spirally disposed portions from the position of the temperature sensing tip up to an edge of the plate; and a light-waveguide element temperature controlled by the temperature controller.
Specifically, according to the invention (15), the light-waveguide device with temperature controller is obtained by combining the temperature controller as defined in the invention (9) according to the invention and the light-waveguide element, thus permitting highly accurate temperature control of the light-waveguide device.
According to the invention (16), there is provided a light-waveguide device a with temperature controller comprising a temperature control element serving for heating or cooling, a temperature control subject component which is temperature controlled by the temperature control element and a plate intervening between the temperature control subject component and the temperature control element, and a temperature sensing element including a temperature sensing tip for detecting temperature and lead lines led out from the temperature sensing tip, wherein the temperature sensing tip is disposed in the plate and the lead lines have meanderingly disposed portions from the position of the temperature sensing tip up to an edge of the plate; and a light-waveguide element temperature controlled by the temperature controller.
Specifically, according to the invention (16), the light-waveguide device with temperature controller is obtained by combining the temperature controller as defined in the invention (10) according to the invention and the light-waveguide element, thus permitting highly accurate temperature control of the light-waveguide device.
According to the invention (17), there is provided the light-waveguide device according to one of the inventions (14) to (16), wherein the temperature sensing tip is disposed at a position corresponding to the central position of the channel waveguide array of the light-waveguide element. Specifically, according to the present invention as defined in the invention (17), for detecting the temperature of the channel waveguide array, which requires constant and highly accurate temperature control, the temperature sensor is disposed at a position corresponding to the central position of the array.
Other objects and features will be clarified from the following description with reference to attached drawings.